<!DOCTYPE html>
<html lang="zh-CN">
    <head>
        <meta charset="UTF-8" />
        <title>01_复习</title>
        <style>
            .outer {
                margin-left: 100px;
                width: 200px;
                height: 200px;
                border:1px solid black;

                transform-style: preserve-3d;

                /* 景深：眼睛距离屏幕的距离   近大远小 */
                perspective: 500px;
            }

            .inner {
                width: 200px;
                height: 200px;
                background-color: aqua;

                transform: rotateX(30deg);
            }
        </style>
    </head>
    <body>
        <!--  -->

        <div class="outer">
            <div class="inner"></div>
        </div>
    </body>
</html>